Imaam al-Asbahaanee (d.535H) - rahimahullaah - said: "The sign of Ahlus-Sunnah is that they follow the Salafus-Saalih and abandon all that is innovated and newly introduced into the Deen." [Al-Hujjah fee Bayaanil Mahajjah 1/364]
Abu Haneefah (d. 150H) (rahimahullaah) said: "Adhere to the athar (narration) and the tareeqah (way) of the Salaf (Pious Predecessors) and beware of newly invented matters for all of it is innovation" [Reported by As-Suyootee in Sawn al Mantaq wal-Kalaam p.32]
lbn Taymiyyah (d.728H) - rahimahullaah - said: "There is no criticism for the one who proclaims the way (madhdhab) of the Salaf, who attaches himself to it and refers to it. Rather, it is obligatory to accept that from him by unanimous agreement (Ittifaaq) because the way (madhdhab) of the Salaf is nothing but the Truth (Haqq)." [Majmoo al-Fataawaa 4:149]
Imaam adh-Dhahabee (d.748H) - rahimahullaah - said: "It is authentically related from ad-Daaraqutnee that he said: There is nothing more despised by me than 'ilmul-kalaam (innovated speech and rhetorics). I say: He never entered into 'ilmul-kalaam, nor argumentation. Rather, was a Salafee (a follower of the Salaf)."[Siyar 16/457]
As-Sam'aanee (d.562H) said in al-lnsaab (3/273): "As-Salafi: this is an ascription to the Salaf and following their ways, in that which is related from them." lbn al-Atheer (d.630H) said in al-Lubaab fee Tahdheebul-lnsaab (2/162), commenting upon the previous saying of as-Sam'aanee: "And a group were known by this ascription." So the meaning is: that the term Salafi, and its ascription to them, was a matter known in the time of Imaam as-Sam'aanee, or before him.